The following abbreviations are herewith defined, at least some of which are referred to within the following description about the prior art and the present invention.    ARP Address Resolution Protocol    BEB Provider Backbone Edge Bridge    B-MAC Backbone MAC address    B-VID Backbone VLAN Identifier    CNP Customer Network Port    FDB Forwarding Database    IP Internet Protocol    I-SID Backbone Service Instance Identifier    L2 Layer 2 (data link layer)    L3 Layer 3 (network layer)    MAC Medium Access Control    MPLS Multiprotocol Label Switching    PB Provider Bridging    PBB Provider Backbone Bridging    PBB-TE Provider Backbone Bridge Traffic Engineering    PEB Provider Edge Bridge    PIP Provider Instance Port    PNP Provider Network Port    PVID Port VLAN Identifier    PWE3 Pseudowire Emulation Edge to Edge    SPB Shortest Path Bridging    TDM Time-Division Multiplexing    VID VLAN Identifier    VLAN Virtual Local Area Network    VPLS Virtual private LAN service
Provider Bridging is the bridging technology deployed today in metro networks (see reference no. 1). A provider may decide to deploy IP/MPLS in its metro network to create the same network environment for services in the metro network as are available in the core network (i.e. the core network is IP/MPLS) to provide standardized L3 or emulated TDM services and at the same time to overcome PB network scalability issues (see reference no. 2). IP/MPLS deployments start with adding IP/MPLS PE nodes as edge nodes to the existing PB metro network. At this stage, IP/MPLS PE nodes are L2 connected by the existing PB transport. The provider may also decide to move its VLAN services to VPLS using the newly deployed IP/MPLS PE nodes (see reference no. 3). This is needed to allow the phasing out of old PB equipment. IP/MPLS PE node deployment is done gradually. Alternatively, the provider may decide to upgrade its PB metro network to provide Provider Backbone Bridging (PBB) (see reference no. 4). PBB overcomes the scalability issues of PB and allows the use of advanced control protocols, such as SPB or PBB-TE. Upgrading a PB edge bridge with PBB functionality is done on a per port basis. After each port upgrade, the provider selects some of its VLAN services to migrate to PBB.
Referring to FIG. 1 (PRIOR ART), there is illustrated an exemplary metro network 100 that depicts when a VLAN service may be migrated to the new technology, i.e. either to VPLS or to PBB, at a stage when some customer sites 102a involved in the VLAN service are still connected to PB edge bridges 104 and other customer sites 102b (related to customer sites 102a) of the same VLAN service are connected to new technology, i.e. VPLS or PBB, edge nodes 106. The motivation to migrate a VLAN service is to reduce the size of a MAC table 108 in PB core bridges 110 (only one shown) located in a PB domain 112 to a larger extent than is possible without the migration of the VLAN services. To provide a VLAN service with edge nodes of different technologies, i.e. either with PB and VPLS or with PB and PBB, coordination is needed between the different technologies and enhanced functionality is needed in the edge nodes of the new technology, i.e. in IP/MPLS PE nodes or in PBB edge bridges. The existing solution for enhancing the functionality in these new technology edge nodes utilizes ARP requests and unknown MAC frame filtering. However, the ARP request and unknown frame filtering method has several problems as follows:                Not transparent to customers                    The customer perceives outages regularly            The customer may receive duplicate frames                        An inter layer solution                    The solution is not a pure Layer 2 solution            The solution is IPv4 specific and not defined for IPv6                        The duration of the outage caused by the method depends on host settings                    Retransmission of lost frames is done by the hosts                        
Accordingly, there has been and is a need to address the aforementioned shortcoming and other shortcomings associated with the prior art to effectively provide a VLAN service in a mixed metro network where the edge nodes include PB edge bridges and PBB edge nodes or IP/MPLS edge nodes. This need and other needs have been satisfied by the present invention.